: Teleportation is a property of Halo. Apparently, a "grid" is needed
: to use it, and Halo has a grid running throughout itself. It's not a
: special ability Cortana gained.

Agreed, but I'm just saying that she gained the ability to perform teleportation using Halo's grid. She was not able to do this prior to being in the mainframe.

: I don't think we've determined conclusively that Cortana is exempt from the
: 7-year lifespan; in fact, I was under the impression that as far as we
: know, she does only have 7 years to live.

Cortana is the first AI to be a direct copy of a human brain. She was made for the sole purpose so that Dr. Halsey's inteligence could live on. Why would they take a direct copy of Dr. Halsey unless they planned on giving the AI an extended life period. If they only wanted Cortana to have a seven year life period, they would have included all the information ever recorded about Human history, but instead they chose to copy a Human. They did this for reasons like they wanted Cortana to have Dr. Halsey's personality. Also, Dr. Halsey was John 117's (Master Chief) best friend. They probably copied Halsey for Master Chief, so that he would always be with her.